1. Field
The present disclosure generally relates to equipment and processes for reworking and/or reinforcing structures, especially composites, and deals more particularly with a method and apparatus for reworking structures from one side thereof.
2. Background
Composite structures sometimes have localized areas containing one or more inconsistencies that may require rework in order to bring the structure within design tolerances, or to reinforce the area.
One technique for reworking localized areas of structures involves mechanically fastening a patch over the area, however fasteners may increase aircraft weight and/or drag on the aircraft, and may be esthetically undesirable in some applications.
Similarly, bonded rework patches may also require the use of mechanical fasteners to provide secondary load paths forming an arrestment mechanism to limit the growth of an inconsistency.
Still another technique for reworking structures, referred to as a wet layup technique, involves hand-layup of wet plies with fiber reinforcement, such as a woven or knitted fabric, and applying wet resin to the plies as they are laid up. The wet layup technique may result in air entrapment within the patch which may form undesirable porosities in the reworked area. These porosities may have an undesirable affect on the reworked area and may make it difficult to verify that a reworked area meets specifications. The wet layup technique may also be labor intensive, require repair technicians to come into proximity with wet resin, and may require excessive cleanup activity.
In some applications, the problems discussed above may be avoided by employing resin infusion of a dry fiber preform patch. After placing a dry fiber preform on a structure such as a scarfed skin, resin is infused into the fiber preform from the outer side of the skin, while excess resin is being drawn out from the preform from the inner side of the skin. This technique, while effective, requires physical access to both sides of the structure, for example, to the inner and outer sides of a skin. Consequently, this technique may not be suitable for use in applications where one side of the structure is difficult or impossible to access.
Accordingly, there is a need for a method and apparatus for reworking structures, especially composites, which reduce or eliminate porosities due to air entrapment. There is also a need for a method and apparatus as described above may be adapted for use in applications where access to only one side of the structure is possible.